Truncated packet support

isPayloadTruncated()
header
[0]: [id=1  ETHERNET   flags=0x4 pre=0 hdr_offset=0    hdr_length=14  gap=0 pay=50  post=0]
[1]: [id=2  IP4        flags=0x4 pre=0 hdr_offset=14   hdr_length=20  gap=0 pay=30  post=0]
[2]: [id=5  UDP        flags=0x4 pre=0 hdr_offset=34   hdr_length=8   gap=0 pay=22  post=0]
[3]: [id=17 RTP        flags=0x4 pre=0 hdr_offset=42   hdr_length=12  gap=0 pay=10  post=0]
[4]: [id=0  PAYLOAD    flags=0x0 pre=0 hdr_offset=54   hdr_length=10  gap=0 pay=0   post=0]
Tcp.isPayloadTruncated

I've checked everything in.